Once Vishwamitra decided to go on mediation as he felt that by doing penance he could rid himself of his anger and jealousy. He prayed with full devotion and seeing his faith and diligence, the gods tired to break his concentration by enticing him with all kinds of attractions. They first sent a beautiful apsara named Menaka, who was a dancer in Lord Indra’s court.
On seeing the beautiful maiden, Vishwamitra gave up his meditation and started pursuing Menaka. It was only after some time he realised the she had been sent by the gods and so he sent her away in anger.
The gods then sent Rambha, another beautiful apsara. But by now Vishwamitra had become aware of the game being played by gods and did not budge from his penance. When she continued enticing him, in anger he cursed her into a stone. Later on, realising that he had been too harsh on her, he felt sorry for the apsara and decided to do penance for failing to control his temper. He meditated for a thousand years, without eating or drinking and subsisting entirely on fresh air. The gods were shocked to see his concentration and turned to Brahma for intervention.
Brahma disguised himself as a beggar and when Vishwamitra was about to break his fast by eating a fruit or two, he appeared in front of Vishwamitra and said, “I have not eaten for the past few days. Can you give me something to eat as I am dying of hunger?”
Vishwamitra replied, “This is all I have and you can take it.”
The beggar then turned into Lord Brahma and said to Vishwamitra, “The amount of hardships you have undergone, you will now be known as Brahmarishi.”
Vishwamitra had observed penance for 1,000 years and with a change of heart, he became friend with Sage Vashishta, with whom he had a strong rivalry since childhood.
It is said that Vishwamitra later became one of the saptarishis, a constellation that shines bright to this day at night.